DPF

Diesel Particulate Filter (DPF) is a device in the exhaust system of many diesel engines designed to reduce emissions by capturing soot and other particulate matter from exhaust gas. The filter is usually a ceramic material, such as cordierite or silicon carbide, shaped into a wall-flow structure that traps soot while allowing gases to pass.

It functions by periodically burning off the accumulated soot in a process called regeneration. Passive regeneration happens automatically when the exhaust temperature is sufficiently high during normal driving, causing soot to oxidize in the filter. If driving conditions do not raise temperatures, active regeneration is triggered by the engine control system, which can inject extra fuel, adjust exhaust flow, or operate a dedicated burner to raise the temperature and oxidize soot. A forced regeneration may be performed by technicians if the filter becomes heavily loaded.

In addition to soot, ash from engine oil accumulates in the DPF and does not burn off. Ash must be removed by servicing or replacement of the filter. Differential pressure sensors monitor soot loading; when backpressure rises, warning lights may illuminate and regeneration may be required.

DPFs are commonly paired with other exhaust aftertreatment components, such as a diesel oxidation catalyst (DOC) upstream and a selective catalytic reduction (SCR) system downstream, to meet emissions standards. They are part of regulatory programs in many regions and tampering or removing a DPF is illegal in many jurisdictions.

Maintenance and lifespan vary with driving patterns and fuel quality, but excessive short trips or frequent idling can lead to clogging and more frequent regenerations. Proper service intervals include periodic cleaning or replacement of the filter.